When communications equipment such as a mobile communication terminal, for example, a mobile telephone is newly developed, some sort of malfunction may be brought about in a mobile telephone in operation, or a mobile telephone in operation has expired a predetermined duration of service in some instances. In such a case, a communication test is required for confirming that various functions of these mobile telephones function normally.
Specifically, there is required a communication test for confirming that it is possible for a mobile telephone serving as a test object for such a communication test to normally execute transmission and reception of various signals to and from a base station.
In this case, in reality, it is impossible to execute a communication test by using a base station in operation. For this reason, the test is performed by using a pseudo-base station device (mobile network simulator device) having the functions of the base station (refer to the following Patent Document 1).
Pat. Document 1: Jpn. Pat. Appln. KOKAI Publication No. 2004-330594
In this communication test using a mobile network simulator device, various signals (modulating signals) are transmitted from a test signal generating apparatus incorporated in the mobile network simulator device to a mobile telephone serving as a test object, in place of a base station. In addition, a reply signal from the mobile telephone is received by a receiver separately provided in the mobile network simulator device. Consequently, a signal level of the reply signal, a content of the reply signal, and the like are checked on, and it is verified whether or not the mobile telephone serving as a test object functions normally.
For example, in order to test a power control function of reply signals of a mobile telephone serving as a test object to a base station, a communication test is performed. The communication test is to confirm that, by sequentially lowering signal levels of test signals to be transmitted to the mobile telephone serving as a test object from the test signal generating apparatus incorporated in a mobile network simulator device, signal levels of reply signals from the mobile telephone serving as a test object sequentially rise.
Further, as shown in FIG. 4, assume a case in which there is a Global System for Mobile Communication (GSM) digital mobile telephone system mode signal within a range (cell) of receiving a Wideband Code Division Multiple Access (WCDMA) signal. In this case, a phenomenon is brought about in which a frequency of the GSM signal discretely moves about a frequency of the WCDMA signal, which results in an interfering wave with mobile telephones in a WCDMA system.
Therefore, frequency hopping is achieved in which a frequency (carrier frequency) of a test signal imitating the GSM signal as described above is changed by a test signal generating apparatus incorporated in a mobile network simulator device, so that a communication test for grasping resistance of a mobile telephone in a WCDMA system serving as a test object with respect to an interfering wave by a GSM signal is executed.
In addition to several communication tests as described above, various communication tests are executed for grasping characteristics of various functions of a mobile telephone based on reply signals of the mobile telephone serving as a test object are executed in such a manner that various test signals are transmitted from the test signal generating apparatus to the mobile telephone serving as a test object.
Accordingly, in a communication test using a mobile network simulator device in this way, a test signal generating apparatus incorporated in the mobile network simulator device is required to prepare test signals having different data, different signal levels, and different frequencies for each of various communication tests.
In the following Patent Document 2, as one of techniques of preparing highly accurate test signals in large quantity and for a short time, there is disclosed some of a technology in which signal waveforms of respective test signals are stored in advance in a memory unit, and the stored signal waveforms are read out to be output as test signals.
Pat. Document 2: Jpn. Pat. Appln. KOKAI Publication No. 7-273555
However, as in the Patent Document 2 described above, there are still the following problems to be solved even in the technology in which signal waveforms stored in advance in a memory unit are read out to be output as test signals.
First, when a frequency hopping signal is generated by using a sequence function of a test signal generator with a wideband width baseband, frequency offset is applied. However, there is a problem that waveform data whose frequency characteristics have been corrected in accordance with the frequency offset must be prepared every frequency offset after high-level accuracy in each hopping frequency is insured.
In this case, frequency characteristics differ each of the respective frequency offsets serving as test objects. For this reason, types of test signals including waveform data whose frequency characteristics have been corrected in accordance with each frequency offset are made to be in vast numbers. Accordingly, there is a problem that a memory capacity required for a memory device such as a hard disk drive which stores respective signal waveforms of those test signals is greatly increased.
Further, in this case, level correction values for correcting frequency characteristics in accordance with each of the respective frequency offsets are stored in advance in a waveform memory, and a frequency characteristic corresponding to each frequency offset is corrected. Consequently, there is a problem that a memory capacity of the waveform memory is greatly increased.
Further, there is a problem that a large amount of labor is required for an operation of generating signal waveforms of test signals having different waveform data, different signal levels, and different frequencies for each of various communication tests for a mobile telephone serving as a test object.
Furthermore, because frequency characteristics differ every mobile telephone serving as a test object, there is a problem that a large amount of labor and time-consuming are required for generating signal waveforms of test signals having frequency characteristics which differ every mobile telephone serving as a test object.
Moreover, in various communication tests for communications equipment such as mobile communication terminals, continuity of frames in a test signal is required. As a consequence, continuity of waveform data at the time of switching the waveforms of the test signal is required, and in many cases, same data is repeatedly used several times depending on a test signal. Therefore, there is a problem that a function of repeatedly outputting same data several times is required in order to insure continuity of waveform data at the time of switching.